Monitor flashes when PC is powered off

I currently built a PC for my daugther’s birthday. It has a Gigabyte GA-7VAX M/B with a AMD Athalon XP 1800+ processor. When I power off the system, it goes through it’s process and shuts down properly. However, after it shuts down, the monitor powers off and then attempts to power on repeatedly. The only way to stop the process is to shut the monitor off manually. Can you give me an idea what potentially may be causing this problem? Thanks